migration at Måkläppen (Falsterbo) 2010 - 2014

Lothar Bach, Petra Bach, Sophie Ehnbom, Måns Karlsson

Introduction Bat migration in Europe is known since Eisentraut (1934) started his bat banding project in 1934, but many facts are still unknown. Generally, migrate and/or hibernate to avoid unfavourable climatic conditions (low winter temperatures) and to avoid low resource levels (Fleming & Eby 2003). In other words, migration enables some bat species to populate higher latitudes with increasing seasonality and decreasing insect production. In contrast to birds, bats can combine migration with hibernation, which results in lower migration distances for bats (Fleming & Eby 2003, Hutterer et al. 2005). Although noctules (Nyctalus noctula) are considered to be partly sedentary in Sweden (Ahlén 2011, Ryberg 1947), Gerell (1987) showed from ringing recoveries that noctules mostly hibernate on the European continent (see also Hutterer et al. 2005). All around the Baltic Sea several departure points are known (Ahlén 1997, Ahlén et al. 2009, Baagøe 2001, Baagøe & Jensen 2007, Meyer 2011, Rydell et al. 2014, Seebens et al. 2013). Ahlén (1997) surveyed bat migration at some well-known bird migration localities and documented at least three bat species (Nyctalus noctula, murinus, nathusii) which left the Swedish coast in direction towards the sea at different places along the Swedish coastline of the Baltic Sea. Ahlén et al. (2009) described several departure points of bats from Gotland, Öland, the Swedish mainland coasts and Denmark (Falster, Bornholm). Ahlén et al. (2007) reported Parti-coloured bats, northern bats, noctules and Nathusius´ bats from a near shore wind farm in Öresund. Klöcker (2002) reported the occurrence of migrating noctules and Nathusius´ bats (Pipistrellus nathusii) in autumn on the island of Fehmarn, Germany. Meyer (2011) confirmed these results and could show during a two-year study, that both species and Pipistrellus pygmaeus regularly passed the island Fehmarn during spring and autumn migration periods. After all it seemed that bats use the same departure points as passerines do in the Baltic Region (Bairlein et al. 2014, Karlsson 2004). Since 2007 an automated detector systems is running to study bat migration along the German East Frisian Islands (Bach et al. 2005, Bach et al. 2009, Frey et al. 2012). Out of that experience and the idea that bats often use the same migration routes as passerines in the Baltic Region (s.o.) we tested whether it was possible to survey bat migration at Måkläppen, since Falsterbo is known as a bird and bat migration point in southern Sweden (Ahlén 1997, Karlsson 2004).

Methods Måkläppen is a small island near the Falsterbo peninsula at the south-westernmost tip of Sweden. The island is a bird- and seal sanctuary and access is prohibited from 1st of February to 31st of October. The bat detector system was situated at the seamark on the outer part of Måkläppen (see fig. 1). A test of the study design was carried out mainly during spring migration in 2010, but also in a small period during autumn migration. After that we tried to survey bat activity at Måkläppen between April and October during in 2012-2014 (tab. 1).

Tab. 1: study periods study period 2010 22.4.-25.6. + 22.9.-16.10. 2012 6.6.-28.10. 2013 22.4. – 20.9. 2014 17.4.-31.10. TM To monitor the bat activity we used the automated bat detector system AnaBat SD1 (Titley Electronics, Australia). The AnaBat system is a so called dividing system and we used the dividing factor 8. The monitoring time was determined between sunset and sunrise. We reloaded the battery with a solar panel and used a modem which allowed us to download the data instantly. Because the system worked well over the whole study period we only had to enter the island for installing and reinstalling the equipment and sometimes to check the system and refine the time for monitoring.

Fig. 1: position of the AnaBat detector at the seamark (left), microphone with reflection mirror (middle) and the solar panel (right).

The positive part of the AnaBat system is, that it creates small file sizes that makes it possible to download data via mobile phone connection. The negative part of that system is that the determination of the bat species is limited due to the dividing system. So in several cases bats can only be determinate up to a genus or group level, such as Pipistrellus spec. or “Nyctaloid” that contains not clearly determinable bats of the genus Nyctalus, and Vespertilio.

Results All together we recorded 7558 bat contacts of at least nine species and the genus Myotis and that cannot be determined further with that detector system. Eptesicus nilsonii (Nordisk fladdermus) was by far the most common bat recorded, followed by Pipistrellus nathusii (Trollfladdermus) and Pipistrellus pygmaeus (Dvärgfladdermus). Most astonishing is the low numbers of Nyctalus noctula (Stor fladdermus), a typical migrating bat species (tab. 1). In several cases Vespertilio murinus (Gråskimlig fladdermus), Nyctalus leisleri (Leislers fladdermus) and Pipistrellus pipistrellus (Pipistrell fladdermus) were recorded. In many cases bat contacts could only determined as “Nyctaloid”, a species group that contains the species of the genus Nyctalus, Eptesicus and Vespertilio (see tab. 1). In every year we recorded bats of the genus Myotis (e.g. Myotis dasycneme – Dammfladdermus) and in 2013 bats of the genus Plecotus (Långörad fladdermus) were recorded. Table 1 shows that most bat species passed Måkläppen every year, while others were recorded only in one (Myotis dasycneme, Plecotus spec.) or few years (Nyctalus leisleri, Vespertilio murinus). However, the last two species might have been overlooked and included in the Group “Nyctaloid” in other years.

Tab. 1: recorded species at Måkläppen 2010 - 2014 Scientific name English name Swedish name 2010 2012 2013 2014 Nyctalus noctula Noctule Stor fladdermus 26 16 94 11 Nyctalus leisleri Leiser´s bat Leislers fladdermus 6 1 Vespertilio murinus Parti-coloured bat Gråskimlig fladdermus 7 18 3 Eptesicus nilssonii Nordisk fladdermus 287 1058 1154 837 Eptesicus serotinus Serotine Sydfladdermus 2 39 22 9 Pipistrellus pygmaeus Soprano Pipstrelle Dvärgfladdermus 53 348 474 260 Pipistrellus nathusii Nathusius´ bats Trollfladdermus 248 523 995 465 Pipistrellus pipistrellus Pipistrelle bat Pipistrelle fladdermus 1 9 82 14 Myotis dasycneme Pond bat Dammfladdermus 1 Nyctaloid* 63 28 111 220 Pipistrellus spec. 4 5 1 4 Myotis spec. 7 7 13 17 Plecotus spec. Long-eared bat Långörad fladdermus 4 * = Group Nyctaloid: Nyctalus, Eptesicus, Vespertilio

Since this investigation was carried out to study bat migration we merely want to focus on the migrating species. The seasonal distribution of Pipistrellus nathusii shows a clear pattern of a migrating species (fig. 2). It appears in early spring with a peak activity around the end of May. After mid-June (as latest) its activity drops and usually does not rise again before mid-August (2012 + 2013). That is when autumn migration starts for this species (see Rydell et al. 2014). Although there are annual differences autumn migration may last until late October (2014).

100 Pipistrellus nathusii 559 2010 (n = 2231) 2012 80 2013 s 2014

60

40

number contact of 20

0

1.5 8.5 5.6 3.7 7.8 4.9

17.4 24.4 15.5 22.5 29.5 12.6 19.6 26.6 10.7 17.7 24.7 31.7 14.8 21.8 28.8 11.9 18.9 25.9 2.10 9.10 16.10 23.10 30.10

Figure 2: seasonal activity of Pipistrellus nathusii 2010-2014

The pattern of activities in Pipstrellus pygmaeus is less clear. Soprano Pipistrelles show only few activities during spring migration. It is as well almost absent during June but occurred regularly during July. In two years (2012 + 2013) it shows a typical pattern of a migrating species with raising activity after mid-August, but in 2014 no peak of activity was found during that time. 140 Pipistrellus pygmaeus 2010 120 (n = 1135) 2012 2013 s 100 2014

80

60

number of contact of number 40

20

0 1.5 8.5 5.6 3.7 7.8 4.9 17.4 24.4 15.5 22.5 29.5 12.6 19.6 26.6 10.7 17.7 24.7 31.7 14.8 21.8 28.8 11.9 18.9 25.9 2.10 9.10 16.10 23.10 30.10

Figure 3: seasonal activity of Pipistrellus pygmaeus 2010-2014

Because of fewer numbers of contacts we summarized all activity data of all investigated years (fig. 4). Higher activity of noctules (Nyctalus noctula) occurred between mid-May and mid-June. After a lack of activity until late July the activity raised again. In contrast Leisler´s bats (Nyctalus leisleri) occurred mainly during the autumn migration period. Parti-coloured bats (Vespertilio murinus) appeared at Måkläppen both during spring and autumn migration and also in July but with few contacts.

20 seasonal bat activity 2010-2014 Nyctalus leisleri (n = 168) Nyctalus noctula

s 15 Vespertilio murinus

10

number of contact of number 5

0 1.5 8.5 5.6 3.7 7.8 4.9 17.4 24.4 15.5 22.5 29.5 12.6 19.6 26.6 10.7 17.7 24.7 31.7 14.8 21.8 28.8 11.9 18.9 25.9 2.10 9.10 16.10 23.10 30.10

Figure 4: seasonal activity of Nyctalus noctula, N. leisleri and Vespertilo murinus 2010-2014

Sedentary northern bats occurred around mid-May and showed a continuous activity until late August/early September (fig. 5). That species is not known as a migrating species in southern Sweden.

200 306 Eptesicus nilsonii 2010 (n = 3336) 2012 2013

s 150 2014

100

number of contact of number 50

0 1.5 8.5 5.6 3.7 7.8 4.9 17.4 24.4 15.5 22.5 29.5 12.6 19.6 26.6 10.7 17.7 24.7 31.7 14.8 21.8 28.8 11.9 18.9 25.9 2.10 9.10 16.10 23.10 30.10

Figure 5: seasonal activity of Eptesicus nilsonii 2010-2014

All other bats species forage at Måkläppen without any seasonal pattern. The overall activity showed a first peak in May, then decreased and increased again in early August.

Discussion It could be shown that Måkläppen is used intensively by foraging and/or migrating bats of at least ten species. Some species are very common (Pipistrellus nathusii, Eptesicus nilsonii) while others are rare (Motis dasycneme, Plecotus spec., Nyctalus leisleri). Although Pipistrellus nathusii and P. pygmaeus is known with nursery roosts in Falsterbo both species show a clear activity pattern corresponding with migration. These results also correspond with the findings of Ahlén (1997) and Ahlén et al (2009). For other species as Nyctalus leisleri and Vespertilio murinus the contacts are too few to show a clear migration pattern, although migration can be assumed. In contrast northern bats, also known to be sedentary at Falsterbo, show a more or less continuous foraging activity at the outer parts of Måkläppen. For Nyctalus noctula the situation is unclear. Hutterer et al. (2005) mention this species as a migrating species also in Scandinavia (see also Gerell 1987). However, this species is also known to be partly sedentary in Sweden (Ahlén 2011, Ryberg 1947). The data for noctules from Måkläppen show a similar pattern as for northern bats. Two species, serotine and pipistrelle bat, are spreading northwards and have reached Falsterbo for several years already (Ahlén 2011). They are regularly foraging at Måkläppen. To clarify the situation of migrating species like noctules, parti-coloured and Leisler´s bats it would be good not only to continue an acoustic monitoring at Måkläppen but also using other methods like bat boxes and mistnetting. Mistnetting would allow taking in hair samples for Stable isotope analyses [Voigt et al. 2012] and ringing would give us a better insight of the bat situation as a whole and the migration of bats at the Falsterbo peninsula in particular. Falsterbo, together with Ottenby (Öland) is predestined as one of the most important place to study bat migration in Sweden.

Acknowledgements We like to thank Jan-Åke Hillarp and Lennart Karlsson for their active support throughout the years. We also like to thank Länsstyrelsen Skåne for permission to work at the nature protection area of Måkläppen. This is Report no. 292 from Falsterbo Bird Observatory.

Literature AHLÉN, I. (1997): Migratory behaviour of bats at south Swedish coasts. Zeitschrift für Säugetierkunde, 62: 375-380. AHLEN, I. (2011): Fladdermusfauna in Sverige. Arternas udbredning och status – Fauna och Flora 106: 2-19. AHLÉN, I., BAAGØE, H.J. & L. BACH (2009): Behaviour of Scandinavian bats during migration and foraging at sea. – Journal of Mammology 90 (6): 1318-1323. AHLÉN, I., L. BACH, H.J. BAAGØE, & J. PETTERSSON (2007): Bats and offshore wind turbines - Final report on 2005-2006 field studies to the Swedish Energy Administration: 17 pp. BAAGØE, H. J. (2001): Danish bats (Mammalia: Chiroptera): Atlas and analysis of distribution, occurrence and abundance. - Steenstrupia (Zoological Museum University of Copenhagen), 26: 1-117. BAAGØE, H.J. AND T.S. JENSEN (Eds.) 2007: Dansk pattedyratlas. Gyldendal, Copenhagen: 392 pp. BACH, L., BACH, P., HELGE, A., MAATZ, K., SCHWARZ, V., TEUSCHER, M. & J. ZÖLLER (2009): Fledermauszug auf Wangerooge - erste Ergebnisse aus dem Jahr 2008. – Natur- und Umweltschutz (Zeitschrift Mellumrat) 8(1): 10-12. BACH, L., C. MEYER-CORDS & P. BOYE (2005): Wanderkorridore für Fledermäuse. - Naturschutz & Biologische Vielfalt 17: 59-69. BAIERLEIN, F., J. DIERSCHKE, V. DIERSCHKE, V. SALEWSKI, O. GEITER, K. HÜPPOP, U. KÖPPEN & W. FIEDLER (2014): Atlas des Vogelzugs. Rongfunde deutscher Brut- und Rastvögel. –AULA-Verlag Wiebelsheim: 567 pp. EISENTRAUT, M. (1934): Markierungsversuche bei Fledermäusen. - Zoomorphology 28 (5): 553–560. FLEMING, T. H. & P. EBY (2003): Ecology of Bat Migration. In: Kunz, T. H. & M. B. Fenton (2003): Bat ecology. – The University of Chicago Press, Chicago, London: 156- 208. FREY, K., BACH, L., BACH, P. & H. BRUNKEN (2012): Fledermauszug entlang der südlichen Nordseeküste. – Naturschutz & Biologische Vielfalt 128: 185-204. GERELL, R. (1987): Flyttar svenska fladdermöss?- Fauna och Flora, 82:79-83. HUTTERER, R., T. IVANOVA, C. MEYER-CORDS & L. RODRIGUES (2005): Bat Migrations in Europe. A review of Banding Data and Literature. – Naturschutz und Biologische Vielfalt 28: 180 S. KARLSSON, L. (2004): Wings over Falsterbo. - Report No. 222 from Falsterbo Bird Observatory. Anser, Supplement 50. Wallin & Dalholm Boktryckeri AB. Lund: 180 S. KLÖCKER, T. (2002): Vergleichende Untersuchung wandernder Fledermausarten in zwei Untersuchungsgebieten Schleswig-Holsteins. – Diploma-Thesis at Rheinischen Friedrich-Wilhelms-Universität Bonn: 137 pp. MEYER, M. M. (2011): Method validation and analysis of bat migration in the Fehmarnbelt area between autumn 2009 and autumn 2010. – unpubl. Thesis, University of Applied Science Osnabrück, 126 pp. RYBERG, O. (1947): Studies on bats and bat parasites. – Stockholm (Svensk Nature). RYDELL, J., L. BACH, P. BACH, L. GUIA-DIAZ, J. FURMANKIEWICZ, N. HAGNER- WAHLSTEN, E.-M. KYHERÖINEN, T. LILLEY, M. MASING, M.M. MEYER, G. PETERSONS, J. ŠUBA, V. VASKO, V.S VINTULIS & A. HEDENSTRÖM (2014): Phenology of migratory bat activity across the Baltic Sea and the south-eastern North Sea. - Acta Chiropterologica 16(1): 139-147. SEEBENS, A., A. FUß, P. ALLGEYER, H. POMMERANZ, M. MÄHLER, H. MATTHES, M. GÖTTSCHE, M. GÖTTSCHE, L. BACH & C. PAATSCH (2013): Fledermauszug im Bereich der deutschen Ostseeküste. – unpubl. report to Bundesamt für Seeschifffahrt und Hydrographie (BSH): 38 pp. VOIGT, C.C, A.G. POPA-LISSEANU, I. NIERMANN & S. KRAMER-SCHADT (2012): The catchment area of wind farms for European bat: a plea for international regulations. – Biological Conservation 153: 80-86.

Dipl. Biol. Petra & Lothar Bach Freilandforschung, zool. Gutachten Hamfhofsweg 125 b, D-28357 Bremen, Germany Phone: +49 (0)421-2768953 Email: [email protected] & [email protected]

Sophie Ehnbom och Måns Karlsson Falsterbo Fågelstation Fyrvägen 35, S-23940 Falsterbo Phone: 040-470688 Email: [email protected] & [email protected]